wp-admin and cloaking…

Ive been thinking of a way to hide the wp-admin folder so the client can log into the backend by typing http://www.clientsite.com/update. Ive looked around on the net and found no solution that works. How about if I set up a domain which cloaked the real url, for example: http://www.clientsite.com/update would point to http://www.clientsite.com/wp-admin. would this work? If so than it would have solved this problem that a lot of people seem to be having.